3D CAD SOFTWARE

I just got a 3D printer and need a 3D cad that handles STL files. There
has to be some software out there that does a simple 3D drawing with out
all the color shading and animation I have looked at OPENSCAD and
BLENDER but they have a totaly different format for drawing then the
AUTOCAD that I am used to.

Any suggestions would be greatly appreciated.

I cannot realy afford the $4000.00 plus for some of them for what I am
going to use it for.

OLD BOB